The present invention relates to a distributed node exchange system, and more particularly to a method of controlling a calling of a distributed node exchange and a distributed node network which are capable of facilitation of processes for calling a plurality of node exchanges for improvement in services to subscribers in a network having a plurality of node exchanges.
As illustrated in FIG. 1, a private exchange comprises a channel switch TDSW, a subscriber circuit LC containing terminals such as telephones, a private circuit TRK connected to private networks 1 and a central processing unit CPU for controlling them and the like. The central processing unit CPU has a calling control section 2 for execution and control of exchange services, a PM scanning section 3 for detecting processing requests from the subscriber circuit LC and from the private circuit TRK, a PM controlling section 4 for sending instructions to the subscriber circuit LC and the private circuit TRK and also controlling them, and a SW switch control section 5 for controlling switching operations of the channel switch TDSW. The control section has interconnections 2-1, TRK call 2-2, TIRK receive 2-3, extension camp-on 24, inter-local camp-on call 2-5, and inter-local camp-on receive 2-5 and others.
This exchange is capable of offering aided services which settle such problems as a difficulty in communication from caller""s terminals to receiver""s terminal due to unavailability in other service of the receiver""s terminal or due to the absence of receiver. Sometimes, the exchange is required to have a special service function and a high service function in response to special functions which might be required, for example, in hotels.
The above private exchange has various service functions, for example, camp-on, call-pickup, conference telephone system, private pocket bell paging and other many service functions.
The conventional exchange is realized by providing separate calling control processors for every services.
As described above, the provide exchange has the various service functions. A plurality of such provide exchanges are interconnected to each other in the form of network to establish the node exchange or the node exchange network system. In those node exchange or the node exchange network system, the exchanges are interconnected via trunk connections such as analog or digital trunks. Signal communications are made for calling control at an interface I/F of each trunk. For this reason, the available amount of the calling control signals in the interface I/F of the each trunk is limited, As a result, the services by connection between the exchanges is considerably inferior to the services by interconnection in a single private exchange. Even if the limitation of the capacity of the trunk interface I/F could be overcome and the trunk interface I/F is added in the calling control section for the calling control processing, at least two calling control processings are required to caller and receiver respectively due to the trunk interface I/F. This makes the calling control processings complicated as compared to the interconnection system.
Further, the exchanges in the network are separate exchanges. Maintenance of the separate exchanges are inconvenient.
In the above circumstances, it had been required to develop a novel method of controlling a calling in distributed node exchange network, a novel distributed node exchange and a novel distributed node exchange network free from the above problems.
Accordingly, it is an object of the present invention to provide a novel method of controlling a calling in distributed node exchange network free from the above problems.
It is a further object of the present invention to provide a novel distributed node exchange free from the above problems.
It is a still further object of the present invention to provide a novel distributed node exchange network free from the above problems.
It is yet a further object of the present invention to provide substantially the same services as when all subscribers in the network are accommodated in a single exchange by substantially the same calling control as in the case of interconnections even the trunk connection is used as the actual interface between the exchanges in a distributed node exchange system having a plurality of exchanges interconnected in network.
It is a further more object of the present invention to enable calling control processings by external interconnections to simplify the calling control processings of the exchanges without providing separate calling control processors for different functions such as trunk call and trunk receive.
It is still more object of the present invention to realize a unified management of the plural nodes in the exchange network having a plurality of nodes.
It is moreover object of the present invention to provide a novel node exchange capable of calling control function and management and use function.
The above and other objects, features and advantages of the present invention will be apparent from the following descriptions.
The present invention provides a method of controlling a call between nodes in a distributed node exchange network having interconnections of plural exchanges, wherein a distributed node has a channel switch, a subscriber circuit, a trunk circuit accommodating local lines and private lines and a processor for controlling a call of the nodes. In a case of connections between the nodes, the node call control processor accommodating call extension lines and the other node call control processor accommodating receiving extension line in correspondence to the call extension lines carry out distributed processings of the call control for providing substantially the same connection services as the interconnection in the node.